Topical anesthetics are a noninvasive means of achieving local anesthesia. This can be especially helpful in children. In some cases, such as IV line placement, topical anesthesia is sufficient for the procedure to be performed. For more involved procedures such as suturing and lumbar puncture, topical anesthetics allows for less painful infiltration of more anesthetic.

EMLA

EMLA (eutectic mixture of local anesthetics) cream contains 2.5% lidocaine and 2.5% prilocaine. It is applied as a thick dollop of cream to the area, and then covered with an occlusive dressing such as Tegaderm. While it provides excellent anesthesia, it must remain on the skin for 60 minutes prior to the procedure to achieve maximum tissue preparation. (Wong, 2003) EMLA is extemely safe to use, but it should not be left on for more than two hours. Cases of methemoglobinemia have been reported (Hahn 1999; Jakobson 1985), however these are exceedingly rare and in most cases involved large doses of EMLA which were in contact with the skin for an extended period of time.

LET

 

LET (lidocaine 4%, epinephrine 0.1%, tetracaine 0.5%) can also be used in a similar fasion to EMLA. It too is generally safe, however should not be used on areas of the body without collateral circulation (such as the fingers, toes, ears and penis) because the epinephrine can cause local tissue ischemia. This is more of a concern when LET is used on lacerations. (Wheaton, 1998)

Benzocaine aerosol (Hurricaine spray)

This topical spray can be used on mucous membranes. Benzocaine spray can be used in the mouth before intraoral injections, and in the oropharynx before nasogastric tube insertion. Benzocaine can cause angiodema and contact dermatitis, and methemoglobinemia in infants.

Anesthesia is achieved within 15-30 seconds, and thus should be applied immediately before the procedure is started. To apply, insert the plastic delivery tube into the top of the aerosol can. Position the tip of the tube 1-2 inches away from the mucosal surface, and spray for 1/2 second. Repeat doses can be administered if desired.

Back | Next